Torque controlled drive



March 18, 1941; V R, w, BAILEY 2,235,192.

. TORQUE CONTROLLED mun I Filed July a1, 1940 spea sheat ATTORNEY.

Patented Mar.-

1941 I Y I UNITED STATES PATENT- ori ice \TORQUE CONTROLLED muvn Roy W. Bailey, Detroit, Mich assignor to Detroit Power Screwdriver Company, Detroit, Mlcln, a corporation of Michigan Application July 31, 1940, Serial N0. 348,638 8 Claims. (Cl. 74- 259) The present invention pertains to a novel two use of like characters which are employed to speed drive controlled by the torque of the load. designate corresponding parts throughout. More specifically, the invention is embodied in a The frame of the machine includes a fixed machine for driving a member such as a stud, table I and a vertical post 2 to which is secured 5 screw or nut and is designed to change its speed a laterally extending bearing arm 3. In the 5 automatically when the unresisted driving action latter is slidably mounted a vertical upper spindle ends and the tightening action begins. More- [actuated to slide up and down at will by any over,'it is another object of the invention to prosuitable means known in the art or by the pedal vide means in the apparatus for terminating the mechanism shown in the patents to F. H. 'Dellaree termined torque is developed. spindle is splined a pulley 5 driven by abelt 6 The invention includes generally an upper or other suitable gearing. It will be noted that driving spindle and a lower driven or work-enthe arm 3 is shaped as a guard l for-such ,a gaging spindle, with transmission gearing and belt 6. clutches between them. A clutch between the The description that follows is not necessarily 15 driving spindle and driven spindle is disengaged in the order of assembly. At the lower end of when the latter is oil the work, while at this time the upper spindle t is a head or casing'B having another clutch locks the gearing to the transmisa reduced upper end 9 enclosing the lower end sion housing. When the spindles are brought of the spindle but spaced therefrom for the inagainst the work, the first clutch engages, and sertion of a bushing ID. A shank Ii is screwed 20 a direct drive resultsbecause of. the locking of into the lower end of the spindle l and is formed the gearing, to the transmission housing by the as a pinion 82 within the casing'll. On the upper secondclutch. face of the pinion is mounted a'collar i3 upon When the actual tightening of the work piece which in turn is mounted a' thrust ball bearing begins, the increased resistance opposes and over- It surrounding the shank II and engaging a comes the second clutch, whereupon the transflange l5 formed on the lowerend of the bushingmission gearing is unlocked and tends to rotate l0. Thus, it will be seen that the casing 3 and the transmission housing oppositely to the drive theparts contained therein are suspended from spindle. The movement of the transmission the collar I 3.

housing is at this time obstructed by a one-way A number of shafts l6, preferably three, are 30 brake engaging the housing, with the result that mounted vertically in the housing at 8 and con- -the latter is stationary and a speed reduction centrically around the gear l2. Each shaft-caris efiected through the gearing.- ries a double gear including a larger gear member The resistance of the brake is limited by an ll, meshing with the pinion l2, and below-it a adjustable spring device so that, when a given smaller gear member IS. The double gears may '35 torque is developed in the load -member, the be either rotatable on fixed shafts It or fixed transmission housing assumes reverse rotation on rotatable shafts. The lower ends of shaftsand absorbs the drive while the driven spindle l6 are received in a lower casing section H at;- remains stationary, thereby indicating the comtached to the main section 8 by bolts 20. Thrust 40 Fiction of the operation. The adjustment of the washers 2| are mounted at both ends of the 40 spring device determines the torque at which double gears to engage the adjacent casing see. the driven spindle ceases to rotate. The appations. ratus is then'removed from the work, whereupon Beneath the gear I! is mount d a lar r and i the driven spindle is de-clutched to resume the 00- 1 8 12 meshing with the smaller ear first described position. members. "and having a shank 23 extending 45 The invention is fully disclosed by way of exloosely into the section I9. The gear itselirests ample in-the following description and in the 119 11 8 ball bearin 24 mounted in the section accompanying drawings in m m. It. In the top of the gear 22 is inserted a disk Figure 1 is an elevation ofthe machine, partly 5 11 whi h is mounted a ball bearing; 26 ena t-- in section; ing the bottom of the pinion l2. Below the disk Figure '2 is a vertical section of thetransmis- 25, the gear 22 and shank 23 are formed with a sion mechanism; cavity 21 reduced at 28 through the lower end Figure 3 is a. plan section of Figure 2, and of the shank. In the reduced portion of the Figure 4 is a plan section in a different plane. cavity is slidably mounted a rod 29 having a Reference to these views will now be made by head II in the larger cavity 21. A spring "in 55 tightening of the load member when a prede- Nos, 1,813,697; 1,862,845 and 1,866,880. On the 10 the cavity bears against the disk 23 and normally holds-the rod 23 in a downward position,

" At the lower face of the casing section I3 is mounted a clutch consisting of a metal disk 32 splined to the shank 23 and disposed between composition disks 33 attached to the section l3 by pins 34. A bottom housing piece 35 is screwed into a sleeve 36 formed at the bottom of the section is. The member 35 has a cavity 31 containing a coil spring bearing against the friction clutch 32, 33 through the medium of a washer 39. Thus, the spring 38 causes the clutch to secure the gear 22 to the section l3 frictionally, at least initially, as will presently appear.

Directly below the clutch 32, 33 another clutch element 40 is screwed on the lower end of the shank 23. A lower spindle 4 is journalled in the member 35 and has a complementary clutch 42 screwed on its upper end. The rod 23 passes 'slidably through the element 40 and abuts the lower spindle 4|, so that the clutch element 42 is normally disengaged from the element 43 under the action of the spring3l. The opposed faces of the members 40 and 42 are formed with radial lugs or abutments 43 adapted for interengagement in driving relation under the conditions presently to be described.

The lower end of the lower spindle 4| is suitably shaped for driving a member by rotation into a body; For-example,'the spindle maybe formed with a wrench socket 44 to receive the head 45 of a screw. Within the scope of the invention, the

. spindle 4| may be formed as a screwdriver. The

raises the upper spindle 4, whereupon the clutch housing 8 is preferably'fille'd with oil in view of which the, member 35 is fitted with an oil seal 43 around the spindle. 4|. r

In the initial operation of the device, the upper spindle. 4 and parts suspended therefrom are lowered, first to engage the work with the lower spindle 4| and next to engage the clutch 40, 42 -in opposition to the spring 3|. As previously stated, the gear 22-is locked to the housing section I3 through clutch 32, 33 under pressure of spring 38. Consequently, all its gears are locked, and

direct drive between upper spindle 4 and lower spindle 4|.

This condition prevails until the torque load exceeds the resistance of the spring-engaged clutch 32, 33, whereupon the latter slips and a speed reduction is introduced. Generally speaking, the direct drive is maintained during unresisted driving of the work piece, and the clutch slips when resistance is introduced by the tightening of the work piece.

As the clutch slips the pinion |2 tends to drive the housing in the opposite direction. This reverse rotation, however,- is resisted by a oneway brake, presently to be described, as a result oi which the drive is transmitted entirelythrough the gears. In the construction shown the reduction is 4 to 1.

The brake is carried by an arm 33 slidably mounted on the post 2 by means of a sleeve ii. The brake consists essentially of two semi-circular shoes surrounding the-housingsection l3 and having a toggle connection permitting the housing to release the brake when turning in one direction and to lock-it when turning in the other direction. One of the shoes 32 is attached direct- 1y to the arm 5] by a pivot pin 33. .The other shoe '4 is formed with a fork BI straddling the arm I. and attached thereto by a pivot pin l4.

' The ends of the fork are fitted with adjustable 7; set screws :1 at opposite sides of the arm n to the entire mechanism turns as a unit, with a limit the movement of the shoe 54 on the pivot.

end 33. The ends of both pivot pins are grooved at 53 to receive the forked ends of a retaining plate which in turn is secured to the arm 33 by a stud 60.

The braking surfaces of the shoes 52 and 34 -'are provided with friction pads 6| or may be fully lined if desired. The free ends of the shoes are extended outwardly in the form of cars 62 and through them is passed a bolt 63. Springs 34 surround the ends of the bolt and bear against the respectively adjacent ears, one spring engaging the bolt head 65 and the other engaging one of a pair of lock nuts 36 on the threaded end.

These springs obviously hold the brake shoes against the member l9. However,. the cars 82 have convex contacting surfaces 31 which permit a rocking actionduring clockwise rotation of the member l9, as the latter movement repels the shoe 34 by turning it on the pivot pin 53. In the opposite direction of rotation, the brake locks the housinguntil the torque-is sufllcient to overcome the springs 64 and repel the shoe 52.

Thesprings 64 are utilized to determine the maximum torque to be applied in tightening the work piece, and this torque is regulated by adjusting the tension of the springs 63, 34, by the lock nuts 66. When the housing is turned against the locking action ofthe brake, the lower spindle 4| is stationary.

When the operator observes the housing turning in the reverse direction, he knows that the work piece has been properly tightened. He then the clutch 40, 42 is disengaged, (.2) direct drive from spindle 4 to spindle 4| while the latter engages the work and spindle 4 is brought down sufiiciently to engage clutch 40, 42 (this is the unresisted driving phase), (3) low speed drivefrom spindle 4 to spindle 4| in tightening the work piece while clutch 32, 33 slips and the housing is locked in the brake, and (4) slippage of the housing in the brake to absorb the drive and leave the lower spindle 4| stationary when the prede- .termined tightening torque has been developed.

Although a specific embodiment of the invention has been illustrated and described, it will be understood that various alterations in the details ofconstruction may be madewithout departing from the scope of the invention as indicated in the appended claims.

What I claim is:

'1..-A drive mechanism comprising a tool driving shaft, a housing rotatably supported thereon, a transmission gear mechanism in said housing and connected to said drive shaft, a driven shaft extending from said housing and adapted to be driven by said transmission mechanism, airlotion clutch normally locking said mechanism to said housing. adapted to slip on development of torque in said driven shaft, and a one-way slip brake engaging said housing, permitting unresisted rotation of said housing in the direction'of said drive shaft and yieldingly resisting rotation in the opposite direction. A

2. A drive mechanism comprising a tool driving shaft, a housing rotatably supported thereon, a transmission gear mechanism in said housing and connected to said drive shaft. a driven shaft extending from said housing adapted to be driven by said transmission mechanism, a friction clutch normally locking said mechanism to said housing, adapted to slip on development of torque in said driven ,shaft, a one-way slip brake engaging said housing, permitting unresisted rotation of said housing in the direction of said drive shaft and housing in said opposite direction, whereby said housingturns in said opposite direction on development of sufficient torque in said driven shaft to overcome said resilient means.

3. A drive mechanism comprising a, tool driving shaft, a housing rotatably supported thereon, a transmission gear mechanism in said housing and connectedto said drive shaft, a driven shaft extending from said housing adapted to be driven by said transmission mechanism, a friction clutch normally locking said mechanism to said housing, adapted to slip on development of torque in said driven shaft, a one-way slip brake engaging said housing, permitting unresisted rotation of said housing in the direction of-said drive shaft and yieldingly resisting rotation in the opposite direction, and adjustable resilient means determining and limiting the resistance of said brake to rotation of said housing in said opposite direction, whereby said housing turns in said opposite 'ditection on development of sufficient torque in said driven shaft to overcome said resilient means.

4. A drive mechanism comprising a tool driving shaft, a housing rotatably supported thereon,

a transmission gear mechanism in said housing and connected to said drive shaft, a driven shaft extending from said housing and adapted to be driven by said transmission mechanism, anda one-way slip brake engaging said housing, permitting unresisted rotation of said housing in the direction of said drive shaft and yieldingly resisting rotation in the opposite direction.

, 5. A drive mechanism comprising a tool driving shaft, a housing rotatably supported thereon,

- a transmission gearmechanism in said housing and connected to said drive shaft, a driven shaft extending from said housing and adapted to be driven by said transmission mechanism, and a one-way slip brake engaging said housing. Dermitting unresisted rotation of said housing in the direction of said drive shaft and yieldingly resist-' ing rotation in the opposite direction, and resilient means determining and limiting the resistance of said brake -to rotation of said housing insaid opposite direction, whereby said housing turns in said opposite direction on development of sufficient torque in said driven shaft to overcome said resilient means.

6. A drive mechanism comprising a tool driving shaft, a housing rotatably supported thereon,

a transmission gear mechanism in said housing and connected to said drive shaft, a driven shaft extending from said housing and adapted to be driven by said transmission mechanism, a clutch between said mechanism and said driven shaft, a spring holding said clutch disengaged when there is no axial pressure on said driven shaft, and a friction clutch normally locking said mechanism to said housing and adapted to slip on development of torque in said driven shaft,an'd a oneway slip brake engaging said housing, permitting unresisted rotation of said housing in the direction of said drive shaft and yieldingly resisting rotation in the opposite direction. 7. A drive mechanism comprising a tool'driving shaft, a housing rotatably supported thereon, a transmission gear mechanism in said housing and connected to said. drive shaft, extending from said housing and adapted to, be driven by said transmission mechanism, a clutch between said mechanism and said driven shaft, a spring holding said clutch disengaged when there is no axial pressure on said driven shaft, a friction clutch normally locking said mechanism to said housing and adapted. to slip on development of torque in said driven shaft, a. one-way slip brake engaging said housing, permitting unresisted rotation of said housing in the direction of said drive shaft and yieldingly resisting rotation in the opposite direction, and resilient means determining and limiting the resistance of said brake to rotation of said housing in said opposite direction, whereby said housing turns in said opposite direction on development of sufficient.

torque in said driven shaft to overcome said resilient means.

8. A drive mechanism comprising a tool driving shaft, a housing rotatably supported thereon, a gear attached to said drive shaft, a driven shaft extending from said housing, another gear in said housing adapted to rotate said driven shaft, re-' .duction gears connecting the first named and second named gears, and a friction clutch normally locking said gears to said housing and adapted to slip on development of torque in said driven shaft, a one-way slip brake engaging said housing, permitting unresisted rotation of said housing in the direction of said drive shaft andyieldingly resisting rotation in the opposite direction, and resilient means determining and limiting the resistance of said brake to rotation of said housing in said opposite direction, whereby said housing turns in said'oppositedirection on de1- velopment of suillcient torque in said driven shaft to overcome said resilient means.

- ROY W. BAILEY.

a driven shaft 20 

